Often the most expensive piece of equipment in the snorkel or personal dive gear package, fins make it possible for snorkelers and divers to swim against currents and waves, carry scuba equipment, and cover more area while snorkeling and diving. As it is sometimes difficult to impossible to swim without fins, the selection of the right fin contributes both to comfort and safety in the water.
There are two types of foot pockets on dive and snorkel fins: full foot and adjustable (sometimes called open heel).
Description: Full foot fins are characterized by a foot pocket that resembles a shoe. The pocket is generally constructed of neoprene or thermoplastic rubber. The diver or snorkeler typically wears the fin barefoot or with a thin neoprene sock. An example of a full foot fin is the Mares Avanti Superchannel.
Preferred by: Full foot fins are often preferred by free divers and snorkels. They are highly efficient when fit properly as they fit snuggly to the foot. Because they are not worn with a boot, the full foot fin does not float at the surface, giving the snorkeler or diver greater thrust as the fin is positioned to take greater advantage of leg strength.
Sizing: Full foot fins require a very precise fit. If they are too small, these fins will cause foot cramps and foot fatigue. If they are too large, they will result in blisters and inefficiency in kicking. Sizing varies by manufacturer and can differ from actual shoe size by as much as 2 sizes. Pocket construction varies by manufacturer and model. Always try on multiple styles to determine which fin will work for you. An experienced sales person in sizing these fins is an invaluable resource.
Pros: More efficient than adjustable fins. Easier to swim with at the surface. Do not require a dive boot.
Cons: Require a very precise fit to ensure comfort and avoid blistering. Can’t be worn in cold water. Difficult to use when entering the water from hot sand and rocky or rough terrain. Leave the ankle exposed to potential scraps and stings.
Description: Adjustable or open heel fins are characterized by a foot pocket made of neoprene or thermoplastic rubber that is open at the heel. A strap across the opening holds the foot in place. Adjustable fins must be worn with boots when scuba diving, though some swim fins and economy snorkel fins can be worn without a boot.
Preferred by: Adjustable fins are often preferred by scuba divers because the boots worn with these fins protect the ankle and foot against scraps and stings, hot and rough terrain when shore diving, and hypothermia in cold water. Because of the neoprene boots, scuba divers also report that adjustable fins often improve buoyancy and trim in the water by preventing the feet from dropping. Adjustable fins have the flexibility to be used in virtually any environment, though they will not perform as well at the surface when snorkeling or in speed and efficiency when free diving.
Sizing: Adjustable fins should be considerably easier to fit than full foot fins. Before sizing the fin, you need to make sure you have a properly sized boot. The fin is sized to the boot worn by the snorkeler or diver, with proper fit generally considered to be the boot heel extending 1 to 3 finger widths beyond the edge of the foot pocket. Any more than three fingers will shift leverage to the diver’s foot rather than the leg causing cramping. Anything less than 1 finger can keep the diver from being able to extend the toes outward, forcing the fin into an inefficient downward position. You should be aware that changing boots can affect the sizing of the adjustable fin. This is the reason that most dry suit divers find they must purchase a separate pair of fins for their dry suit. A more substantial or rigid sole on the boot often requires a different fin size.
Strap design: Adjustable fins can come with different kinds of straps. The most common strap is made of rubber and threads through clips attached to the side of the foot pocket. These clips attach to posts that are normally a molded part of the fin. Spring straps or band straps are relatively new and were adopted early on by the technical diving community. These straps are made of either stainless steel or stretchable rubber. The advantage of these straps is that they make it easy to get the fin on and off. They also are nearly indestructible, making it unlikely that they will break.
Pros: Versatile–can be used for nearly any kind of snorkeling or diving. Easier to size. Often more comfortable as the boot used with these fins protects the foot and ankle.
Cons: Difficult to use on the surface. Not as efficient a full foot fins. Requires a boot (extra equipment). Cost more.
The blade is the flat surface of the fin that pushes the water as you kick. There are several different types of fin blades. The type of blade determines the power of the fin, how hard it is to kick, and what style of kick you will need to drive the fin. Here are some of the common blade types.
Standard Fins. The blade on a standard fin is generally a flat surface. It does not have vents, channel, splits, or hinges. These are generally the least expensive and least efficient fins. Note that all standard fins are not created equal. Some have sophisticated ridges that stabilize the fin as you kick. Some are also curved to improve thrust. An example of a high quality standard fin is the Atomic Blade Fin.
Vented Fins. Vented blades have been around for years. The neoprene injected fins of the 1970s are good examples of vented fins. However, these fins are still being manufactured and remain popular with cave divers and wreck divers as they do not stir up the bottom like other fins. An example of a current vented fin is the Mares Power Plana Fin.
Channel Fins. These fins have channels often made of a softer material like neoprene and separates panels of thermoplastic. These channels give the fin more flexibility, causing it to cup the water as the diver kicks. This cupping action reduces stress on the diver’s leg while allowing a larger volume of water to be driven with each kick. A well-known example of the channel fin is the Mares Avanti Quattro.
Split Fins. Split fins are characterized by a split down the middle of the fin blade. When compared to standard blades, split fins tend to deliver more propulsion with less drag and kick with less effort by allowing the blade to flex outward. These fins often provide greater sustained speed , but they sometimes provide less power than a standard or channel fin. The most famous split fin is probably the Atomic Split Fin.
Hinged Fins. Sometimes referred to as an Optimized Pivoting Blade (OPB), the hinged fin is one of the newer blade types. They are characterized by a hinge or mechanize near the middle of the blade that causes the end of the blade snap up and down while reducing stress on the diver’s leg. These fins tend to be more powerful than split fins while providing the same easy kick. An example of the hinged fin is the Mares X-Stream.
Free Diving Fins. Free diving fins are characterized by very long blades. The blades are often made of light, high performance materials like carbon fiber. While sometimes difficult to kick initially, these fins flex rapidly once the blade is in motion, making for an incredibily efficient and powerful kick. Most free diving fins are also constructed so that the diver can interchange blades on the same foot pocket. This is popular with underwater hunters who may wish to use different types of camo blades. An example of the free diving fin is the Mares Razor Pro.
Here are some things to remember when buying fins.